A virtual machine (VM) is an emulation of a computer system. When executed on appropriate hardware, a VM creates an environment allowing the virtualization of an actual physical computer system (e.g., a server, a mainframe computer, etc.). The actual physical computer system is typically referred to as a “host machine.” Typically, a component on the host machine known as a “hypervisor” (or a “virtual machine monitor”) manages the execution of one or more virtual machines or “guests”, providing a variety of functions such as virtualizing and allocating resources, context switching among virtual machines, etc. The operating system (OS) of the virtual machine is typically referred to as the “guest operating system” or “guest OS.” In some implementations, the guest OS and applications executing within the guest OS can be collectively referred to as the “guest.”
Physical devices, such as network devices or video cards, can be made available to guests by the hypervisor by a process known as “device assignment.” The guest can create a virtual device that is to be associated with a physical device so that any access of the virtual device can be forwarded to the physical device by the hypervisor with little or no modification